In a hypersonic aircraft that includes a scramjet engine, forward speed of the hypersonic aircraft compresses supersonic airflow as it enters a duct of an air inlet of the scramjet engine and passes through the scramjet engine. This compression increases the air pressure higher than that of the surrounding air. In a combustor of the scramjet engine, fuel is ignited in the supersonic airflow. Rapid expansion of hot air out an exhaust nozzle of the scramjet engine produces thrust.
The optimum shape of the duct depends on speed of the hypersonic aircraft. Therefore, for optimum performance the shape of the duct must change as the hypersonic aircraft flies. Typically, shape of the duct has been changed by mechanically moving large panels. This approach involves use of hinges and sliding mechanisms, which are heavy and can experience difficulties with hot seals.
A hypersonic aircraft also includes control surfaces, such as flaps, that are actuated during flight. Typically, control surfaces in hypersonic aircraft have also been actuated mechanically, such as by use of hinges, spindles, and sliding mechanisms. Difficulties have been encountered in controlling temperatures around the spindle. Mechanically actuating the flaps creates a sharp change in angle over the surface of the hypersonic aircraft. This sharp change in angle can cause a separation of flow. Subsequent reattachment of flow causes heating at the reattachment point.
Therefore, it would be desirable to change shape of the duct without use of heavy mechanical actuators and their associated difficulties with hot seals. It would also be desirable to change shape of control surfaces smoothly rather than creating sharp angles and the associated heating due to separation and subsequent reattachment of flow.
The foregoing examples of related art and limitations associated therewith are intended to be illustrative and not exclusive. Other limitations of the related art will become apparent to those of skill in the art upon a reading of the specification and a study of the drawings.